Cycle Basics
The 4 stages of the estrous cycle in order are?
What is Proestrus → Estrus → Metestrus → Diestrus
This hormone is at it highest during Dietrus
Progesterone
This is the stage that the female is receptive to the male
Estrus
The best stage to breed a female is
Estrus
Estrogen is rising and follicles are growing—what stage is this?
Proestrus
Which stage is known as “standing heat”?
What is Estrus
This hormone greatly increases leading up to Estrus
What is Estrogen
During which stage does ovulation occur (just after heat)?
Metestrus
To wait because she will not be receptive and explain that she will need to be breed before ovulation.
During the Follicular phase of the Estrous Cycle what hormone is dominant?
Estrogen
The longest stage in the estrous cycle is
Diestrus
The surge of this hormone is responsible for triggering ovulation
Luteinizing Hormone - LH
This is the stage that is responsible for performing the corpus luteum or the yellow bobdy.
Metestrus
A farmer tells you that hes breeding his cows this week because progesterone is high and you should breed while hormone are high. What stage is he likley trying to breed them in and why is it wrong?
Diestrus, and there is no egg to fertilize because it is well past ovulation
Progesterone is high and ovulation is inhibited—what stage?
Diestrus
Which stage do follicles begin rapidly growing before heat?
What is Proestrus?
This hormone prevents the female from returing to estrus and is repsonible for preparing the uterus and maintaing pregnancy
What is Progesterone
This is the stage in which the corpus luteum begins regressing causing estrogen to rise and follicles to being growing again.
Proestrus
A farmer breeds at the very end of estrus, what risk does this create?
Lower chance of fertilization, might miss ovulation timing.
It is day 20 of the Estrous cycle, the female is not pregnant, but progesterone remains high—what likely failed to occur?
Corpus luteum did not regress
Diestrus is an important stage in the Estrous Cycle, theoretically what would happen if it did not occur?
The uterus would not be able to maintain a pregnancy because there would be no progesterone.
This hormone is responsible for follicle development that eventually releases the egg. What is it?
Follicle Stimulting Hormone - FSH
Ovulation is the release of the egg from the follicle, if ovuation failed to occur how would that change the cycle?
No corpus luteum could grow from the follicle -> low progesterone -> No Diestrus would occur -> proestrus would start immediatly. = Cycle is disrupted or shortened.
A farmer wants to maximize pregnancy success. Explain the biological reason timing breeding before ovulation is important.
Sperm must be present when egg is released; egg has short lifespan, sperm need time to travel
Predict what would happen if LH was never released during the cycle.
No ovulation → no corpus luteum → no progesterone rise → cycle cannot proceed normally